Give Pyright what it wants (alias attributes everywhere)

newsfragments/3114.bugfix.rst

@@ -0,0 +1 @@
+Ensure that Pyright recognizes our underscore prefixed attributes for attrs classes.

pyproject.toml

@@ -189,7 +189,7 @@ reportUnnecessaryTypeIgnoreComment = true
 typeCheckingMode = "strict"
 
 [tool.pytest.ini_options]
-addopts = ["--strict-markers", "--strict-config", "-p trio._tests.pytest_plugin"]
+addopts = ["--strict-markers", "--strict-config", "-p _trio_check_attrs_aliases", "-p trio._tests.pytest_plugin"]
 faulthandler_timeout = 60
 filterwarnings = [
   "error",

src/_trio_check_attrs_aliases.py

@@ -0,0 +1,22 @@
+"""Conftest is executed by Pytest before test modules.
+
+We use this to monkeypatch attrs.field(), so that we can detect if aliases are used for test_exports.
+"""
+
+from typing import Any
+
+import attrs
+
+orig_field = attrs.field
+
+
+def field(**kwargs: Any) -> Any:
+    original_args = kwargs.copy()
+    metadata = kwargs.setdefault("metadata", {})
+    metadata["original_args"] = original_args
+    return orig_field(**kwargs)
+
+
+# Mark it as being ours, so the test knows it can actually run.
+field.trio_modded = True  # type: ignore
+attrs.field = field

src/trio/_core/_local.py

@@ -38,8 +38,8 @@ class RunVar(Generic[T]):
 
     """
 
-    _name: str
-    _default: T | type[_NoValue] = _NoValue
+    _name: str = attrs.field(alias="name")
+    _default: T | type[_NoValue] = attrs.field(default=_NoValue, alias="default")
 
     def get(self, default: T | type[_NoValue] = _NoValue) -> T:
         """Gets the value of this :class:`RunVar` for the current run call."""

src/trio/_core/_run.py

@@ -544,9 +544,13 @@ class CancelScope:
     cancelled_caught: bool = attrs.field(default=False, init=False)
 
     # Constructor arguments:
-    _relative_deadline: float = attrs.field(default=inf, kw_only=True)
-    _deadline: float = attrs.field(default=inf, kw_only=True)
-    _shield: bool = attrs.field(default=False, kw_only=True)
+    _relative_deadline: float = attrs.field(
+        default=inf,
+        kw_only=True,
+        alias="relative_deadline",
+    )
+    _deadline: float = attrs.field(default=inf, kw_only=True, alias="deadline")
+    _shield: bool = attrs.field(default=False, kw_only=True, alias="shield")
 
     def __attrs_post_init__(self) -> None:
         if isnan(self._deadline):

src/trio/_tests/test_exports.py

@@ -572,3 +572,37 @@ def test_classes_are_final() -> None:
                 continue
 
             assert class_is_final(class_)
+
+
+# Plugin might not be running, especially if running from an installed version.
+@pytest.mark.skipif(
+    not hasattr(attrs.field, "trio_modded"),
+    reason="Pytest plugin not installed.",
+)
+def test_pyright_recognizes_init_attributes() -> None:
+    """Check whether we provide `alias` for all underscore prefixed attributes.
+
+    Attrs always sets the `alias` attribute on fields, so a pytest plugin is used
+    to monkeypatch `field()` to record whether an alias was defined in the metadata.
+    See `_trio_check_attrs_aliases`.
+    """
+    for module in PUBLIC_MODULES:
+        for class_ in module.__dict__.values():
+            if not attrs.has(class_):
+                continue
+            if isinstance(class_, _util.NoPublicConstructor):
+                continue
+
+            attributes = [
+                attr
+                for attr in attrs.fields(class_)
+                if attr.init
+                if attr.alias
+                not in (
+                    attr.name,
+                    # original_args may not be present in autoattribs
+                    attr.metadata.get("original_args", {}).get("alias"),
+                )
+            ]
+
+            assert attributes == [], class_